The invention relates to a system for displaying vital sign data. More particularly, the invention relates to a system for simultaneously measuring and monitoring electroencephalograms of a number of patients by use of a plurality of electroencephalographs.
Conventionally, an electroencephalograph has successively displayed, on a display section, an electroencephalogram derived from electrodes by way of a junction box, analysis data (a frequency spectrum) obtained through analysis of the electroencephalogram, or the like, and recorded the same in a recorder; or stored the same in a storage. In addition, there have hitherto been practiced long-hour measurement; application of an auditory or a photo stimulation to the patient; or capture of an image of a patient by a video camera with permission from the patient for the purpose of monitoring the state of the patient. The thus-obtained image is displayed on a display of the electroencephalograph in conjunction with electroencephalographic waveforms and the analysis data.
Japanese Patent Publication No. 2002-541891A discloses a technique of displaying an electroencephalographic waveform on the upper left portion of the screen, and an image showing a state of a patient captured by a video camera on the lower right portion, thereby displaying these on a single screen.
Japanese Patent Publication No. 2003-79591A discloses a method of displaying on a single screen an electroencephalographic waveform per se and a DSA (density spectral array) obtained through analysis of the electroencephalogram.
Meanwhile, a DSA display method is such a display method that an electroencephalogram is subjected to FFT (fast Fourier transform); and a bar-shaped image is displayed at a predetermined time interval while the density of dots (black dots) of the bar is changed or the color of the same is changed in accordance with the amplitude of the electroencephalogram obtained after the FFT analysis, wherein the Y axis represents a frequency, and the X axis represents time.
As described above, electroencephalography is usually performed with use of a single electroencephalograph per patient to be measured, while a technician is on standby at the electroencephalograph. During measurement, the technician must monitor the state of electroencephalograms displayed on a screen of the electroencephalograph and an image of the patient displayed on a screen, thereby maintaining such a condition that, in the event of detachment of electrodes attached on the patient, occurrence of an abnormal condition to the patient, or the like, the technician can respond immediately.
However, in an epilepsy-specialized hospital, or the like, electroencephalograms of a plurality of patients must be measured continuously over several hours, over several days, or, in a case of long-term measurement, over one week under patient-specific conditions. In such a case, a single technician is to be assigned for a single electroencephalograph. However, since an abnormal condition rarely occurs in a patient, provision of a single technician for a single electroencephalograph over several days to one week has been unrealistic. To this end, for the purpose of reducing the number of technicians, the following method has been proposed.
Namely, as an easy and convenient method for solving the problem, there has been proposed a method of displaying and monitoring only video signals output from respective video cameras on a single monitor in a centralized manner by screen splitting so as to monitor only measurement states of patients. In this case, since only states of the patients are monitored in the form of video images without monitoring electroencephalograms, there has arisen a problem that insufficient information poses difficulty in making appropriate response.
Alternatively, as another method, displaying electroencephalograms output from electroencephalographs and video signals output from video cameras on a central control monitor is also conceivable. However, electroencephalograms output from a single electroencephalograph number from, even in a minimum volume, 32 channels to, in a case of a large volume, as many as 250 channels. Accordingly, connection of a plurality of electroencephalographs to a single central control monitor, to thus perform display, has encountered technical difficulty in implementation because of problems in signal sampling, shortage in data transfer rate or processing data rate of a communication network, and like problems.